dack vs relax

dack

verb
  • To pull down someone's trousers as a practical joke. 

relax

verb
  • To make something loose. 

  • To become loose. 

  • To become less severe or tense. 

  • To make something (such as codes and regulations) more lenient. 

  • To calm down. 

  • To relieve (something) from stress. 

  • To make something less severe or tense. 

  • To become more lenient. 

How often have the words dack and relax occurred in a corpus of books? (source: Google Ngram Viewer )